Background:Muscle involvement is the most frequent clinical feature in patients with idiopathic inflammatory myopathies (IIM). In addition to muscular enzymes, muscular magnetic resonance has been investigated for the assessment of disease activity, but it is limited by high costs and it is not readily available. Muscle ultrasound (MUS) has been recently proposed as a valuable tool for the diagnosis and activity assessment of muscle involvement in IIM patients.Objectives:To define the role of MUS in the diagnosis and assessment of disease activity in IIM through quantitative analysis of MUSMethods:This was a prospective study conducted from February 2019 to November 2019. 41 patients with IIM: 17 men and 24 women, median age 61.4 years, of which 20 were polymyositis (PM), 16 dermatomyositis (DM) and 5 inclusion body myositis (IBM) were included. 30 healthy subjects (HS), comparable in age and gender to patients, were recruited as controls. In every patient and control MUS of upper and lower extremities was performed (in total 10 muscles per side) and digital images were saved. Quantitative muscle echo intensity (QME) was calculated using an image processing program (ImageJ) to obtain the mean value of greyscale (mGS) for each muscle. For patients with IIM creatine phosphokinase (CPK) levels were recorded, duration of disease (in months) was calculated and clinical evaluation tools for the assessment of disease activity were performed, such as manual muscle testing (MMT8), patient and physician visual analogue scales (pVAS, phVAS), health assessment questionnaire (HAQ) and myositis disease activity assessment tool (MDAAT).Results:Patients had higher values of mGS across all muscles examined than controls (p<0.001). Among patients QME showed a negative correlation with MMT8 (p<0.001, -0.641<r<-0.412), but no correlation with CPK levels or duration of disease. A positive correlation was found between QME and HAQ (p<0.05; 0.320<r<0.599), pVAS (0.003<p<0.046; 0.314<r<0.455) and phVAS (0.029<p<0.002; 0.341<r<0.471). No significant correlation was found between QME and MDAAT and no statistically significant differences of muscle echo intensity were observed between patients with IBM, DM and PM.Conclusion:Quantitative analysis of MUS showed to be useful to differentiate IIM patients from healthy subjects, therefore it could be a helpful technique to screen patients with muscular symptoms in which perform additional investigations. In our study, the data collected did not allow to assess the disease activity of IIM patients and did not allow to distinguish between the 3 different subgroups of IIM patients, but further studies may help in the identification of different muscular patterns to guide the clinical suspect and the possible role of MUS in the follow-up of the patients.Disclosure of Interests:Alessandra Tripoli: None declared, Simone Barsotti: None declared, Andrea Delle Sedie Speakers bureau: MSD, Lilly, Novartis, Abbvie, Celgene, Giacomo Aringhieri: None declared, Saverio Vitali: None declared, Rossella Neri: None declared, Davide Caramella: None declared, Marta Mosca: None declared
Association between echo intensity and attenuation of skeletal muscle in young and older adults: a comparison between ultrasonography and computed tomography
